Hello Kurt,
Thanks for looking at this problem.
The project manager works for a licensed PV contracting company that has been
trying for several months to get this PV system approved. First, they were
blocked by the Los Angeles Building & Planning's interpretation of the LA Fire
Marshall's set-back guidelines (not regulations). Now LADWP's interconnection
department is holding up the project. If the system had been installed last
year as planned, this new rule would not have applied. There is no requirement
like this in nearby Southern California Edison (SCE) territory.
(Pulling the meter is not acceptable to most fire departments, but that's a
separate subject.)
My question is Do any other electric utilities require an additional disconnect
switch on a PV system with a line-side tap?
Joel Davidson
----- Original Message -----
From: Kurt Albershardt
To: RE-wrenches
Sent: Saturday, February 21, 2009 12:08 PM
Subject: Re: [RE-wrenches] 2 PV utility interconnect disconnects?
On 2/21/09 10:24 AM, Joel Davidson wrote:
January 1, 2009 LADWP added another interconnection requirement. See page
8-11 at http://www.ladwp.com/ladwp/cms/ladwp004344.pdf
I found what I think is the relevant section on p. 36 of the PDF (called out
as p. 1-32 at the top of the page.)
This is how a PV commercial project manager described this new requirement:
I'm curious if this was an LADWP project manager, or someone managing
projects for customers?
When a customer, any customer, generates electrical power with the
intention of supplying that power to the electrical grid, the connection to the
grid has to be made below, or on the load-side, of one main switch for the
property.
They define
generators using a closed-transition (“make-before-break”) type transfer
switch or a multi-
breaker transfer scheme, or an electrical inverter that can be configured to
operate in a utility
interactive mode constitute a potential back feed source into the
Department’s electric system and are
classified as interactive generators.
the policy seems to be that the total electricity supplied to any building
or property must be disconnected from the grid by one main switch.
The wording appears to be:
All interconnected generating systems shall be connected on the load side of
the customer’s meter switch (main service disconnect device).
I'm wondering about the origins of this requirement. How would they handle
critical power systems (data centers, hospitals, etc. which are often fed by
multiple services entering by different routes?) How would they handle a
premises with multiple service voltages?
This policy is in place for emergency situations, to where fire fighters or
persons on the scene during an emergency would be able to completely shut down
building power with one switch.
The phrase "pull the meter" comes to mind here...
This describes a scenario whereby the grid is disconnected from the
building circuits, but the solar PV is still connected to the building
circuits. Therefore, there is a basic flaw in this requirement; this scenario
is only possible at nighttime- during the daytime, the solar PV system is
energized and may still feed to the building electrical circuits, unless the
main PV disconnect switch is opened.
Has this "project manager" ever heard of anti-islanding? This fantasy
scenario almost makes sense for a battery-backed PV system, but then the
presence or absence of sunshine would not matter. What about emergency backup
gensets and UPS or flywheel systems? They are protected from backfeeding by a
transfer switch, so exempted, but UL 1741 does not qualify as such?
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